A welding fume collection process that meets the Laboratory Method for Measuring Fume Generation Rates and Total Fume Emission of Welding and Allied Processes, ANSI/AWS F1.2-92 and AWS F1.2:1999 uses a fume collection chamber. With reference to FIG. 1, a known fume collection chamber A includes a circular chamber housing B upon which a conical hood C is permanently welded. The conical hood C communicates with a vacuum source, which is provided by an air line hose D connected to a Venturri apparatus, to provide an airflow in the chamber so that welding fumes can be collected.
A primary filter E is disposed inside and near the top of the conical hood C. The primary filter E is sealed by compressing the filter around a rubber gasket F attached to a screen G, which is attached to the conical hood C. The primary filter E is made from a material that can allow the passage of fine particles in the fume emissions, especially during the initial start up of the test. Accordingly, a secondary filter H is disposed in a cylindrical filter housing I that is in communication with the conical hood C. The air line D also communicates with the secondary filter housing I so that air is drawn through the housing. Welding is performed on a turntable J disposed in the housing.
Loading and changing of the primary filter E requires tilting back nearly the entire assembly on hinges K. Removal and installation of the primary filter E is done from inside the chamber. During a test, the primary filter E can fall out of the gasket F and/or lose its seal, whereby an airflow path can develop bypassing the primary filter, which results in an unusable test. While running the test, one is unable to determine whether the primary filter E has fallen out or lost its seal. Furthermore, emissions that pass through both the filters E and H can travel through the air line hose D en route to a muffler (not shown), which can result in blockage in the muffler and loss of vacuum pressure in the chamber. Also, airflow through the chamber is difficult to regulate.